linux-kernel - Re: [PATCH v9 27/32] timers: Check if timers base is handled already

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Message-ID: <20231206105806.e4A02OHA@linutronix.de>
Date:   Wed, 6 Dec 2023 11:58:06 +0100
From:   Sebastian Siewior <bigeasy@...utronix.de>
To:     Anna-Maria Behnsen <anna-maria@...utronix.de>
Cc:     linux-kernel@...r.kernel.org,
        Peter Zijlstra <peterz@...radead.org>,
        John Stultz <jstultz@...gle.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Eric Dumazet <edumazet@...gle.com>,
        "Rafael J . Wysocki" <rafael.j.wysocki@...el.com>,
        Arjan van de Ven <arjan@...radead.org>,
        "Paul E . McKenney" <paulmck@...nel.org>,
        Frederic Weisbecker <frederic@...nel.org>,
        Rik van Riel <riel@...riel.com>,
        Steven Rostedt <rostedt@...dmis.org>,
        Giovanni Gherdovich <ggherdovich@...e.cz>,
        Lukasz Luba <lukasz.luba@....com>,
        "Gautham R . Shenoy" <gautham.shenoy@....com>,
        Srinivas Pandruvada <srinivas.pandruvada@...el.com>,
        K Prateek Nayak <kprateek.nayak@....com>
Subject: Re: [PATCH v9 27/32] timers: Check if timers base is handled already

On 2023-12-01 10:26:49 [+0100], Anna-Maria Behnsen wrote:
> Due to the conversion of the NOHZ timer placement to a pull at expiry
> time model, the per CPU timer bases with non pinned timers are no
> longer handled only by the local CPU. In case a remote CPU already
> expires the non pinned timers base of the local cpu, nothing more
                                                  CPU

so it is consistent with the other.

> needs to be done by the local CPU. A check at the begin of the expire
> timers routine is required, because timer base lock is dropped before
> executing the timer callback function.
> 
> This is a preparatory work, but has no functional impact right now.
> 
> Signed-off-by: Anna-Maria Behnsen <anna-maria@...utronix.de>

Sebastian